This article will see how to check if a string is empty using different methods and various examples.
Table of Contents:-
- Javascript check if string is empty using === operator
- Javascript check if string is empty using length and ! operator
- Javascript check if string is empty or has only white spaces
- Javascript check if string is valid using typecasting
- Javascript check if string is empty using replace
- Javascript check if string is empty using case statement
Javascript check if string is empty using === operator
In the below example, a function is used to determine if the string is empty or not. If blank, the function will print The string is empty else, it will print The string is not empty.
function isEmptyCheck(string1) { if (string1 === "") { console.log("The string is empty") } else{ console.log("The string is not empty") } } isEmptyCheck("") isEmptyCheck("Hello Javascript")
Output:-
The string is empty The string is not empty
Javascript check if string is empty using length and ! operator
In the below example, a function will determine if the string is empty or not. If empty, the function returns true else it will return false.
Frequently Asked:
function isEmptyFunction(_string) { return (!_string || _string.length === 0 ); } console.log(isEmptyFunction("")) console.log(isEmptyFunction("Hello Javascript"))
Output:-
true false
Javascript check if string is empty or has only white spaces
In the below example, the function will determine if the string is empty or not or has only white spaces. The function would return true if the string passed as an argument is empty or has only white spaces. The function returns false for other inputs.
function isEmptyFunction2(_string1) { return (_string1.length === 0 || !_string1.trim()); }; console.log(isEmptyFunction2("Hello Javascript")) console.log(isEmptyFunction2("")) console.log(isEmptyFunction2(" "))
Output:-
false true true
Important Note: The function will return an error “trim is not a function” if the input argument passed is not a string.
Javascript check if string is valid using typecasting
In the below example, the function will determine if the string is valid or not. The function will typecast the variable to Boolean. The function prints The string is improper when null, undefined, 0, 000, “”, false are input arguments and The string is proper when a string, “0” and whitespace are input arguments.
function isImproperStringCheck(_stringInput) { if (Boolean(_stringInput)) { console.log("The string is proper") //false for null, undefined, 0, 000, "", false. } else{ console.log("The string is improper") //true for string "0" and whitespace " ". } } isImproperStringCheck("") isImproperStringCheck(" ") isImproperStringCheck("Hello Javascript") isImproperStringCheck(0) isImproperStringCheck("0")
Output:-
The string is improper The string is proper The string is proper The string is improper The string is proper
Javascript check if string is empty using replace
In the below example, the function will determine if the string is empty or not. The function will print The string is blank in case the string is empty or has only white spaces. Else will print The string is not blank
function isEmptyCheck(_string) { if(_string.replace(/\s/g,"") == ""){ console.log("The string is blank") }else{ console.log("The string is not blank") } } isEmptyCheck("") isEmptyCheck(" ") isEmptyCheck("Hello Javascript")
Output:-
The string is blank The string is blank The string is not blank
Important Note: The function will return an error “replace is not a function” if the input argument passed is not a string.
Javascript check if string is empty using case statement
In the below example, the function will check different cases and print String is empty/null/undefined/0 if the input argument is empty, null, undefined, false, or 0 else will print String input is valid.
function check_empty(_string) { switch (_string) { case "": case null: case false: case 0: case typeof(_string) == "undefined": return "String is empty/null/undefined/0"; default: return "String input is valid"; } } console.log(check_empty(null)) console.log(check_empty("Hello Javascript")) console.log(check_empty(0)) console.log(check_empty(7) ) console.log(check_empty(""))
Output:-
String is empty/null/undefined/0 String input is valid String is empty/null/undefined/0 String input is valid String is empty/null/undefined/0
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We hope this article helped you to check if a string is empty in javascript. Good Luck !!!